Recording and reproduction in a magnetic recording device for audio, video or computer applications are generally performed by contact sliding between a magnetic head and a magnetic recording medium, e.g., magnetic tape. If contaminated with adherent debris (stains) from tape dust or surrounding dust, the magnetic head has reduced reproduction output and eventually fails to produce output. In order to restore the reduced reproduction output, a cleaning medium, such as a cleaning tape, is used to remove the adherent stains from the surface of the magnetic head.
On the other hand, magnetic recording density has been increasing every year. Unless a magnetic head and magnetic tape are in good contact, failure to achieve sufficient writing and reading would be experienced more frequently. To maintain a good head contact, a cleaning tape has come to be required to perform not only the head cleaning function but also a function to regulate the shape of a head to some extent. In particular, a magnetic head used in recent magnetic recording devices capable of high density recording at a shortest recording wavelength of 1 μm or less has a gap length of 0.4 μm or less. Even a trace of dirt or dust on such a magnetic head would interfere with read performance.
With the ever increasing recording density, a magneto-resistive (MR) head has come into use. A shielded MR head for general use has a height of several microns or less. Accordingly, wear of an MR head should be minimized more strictly than demanded for conventional ferrite heads or metal heads (e.g., a Sendust head).
In recent years, magnetic recording devices capable of using both an ME (metal evaporate) tape and an MP (metal particle) tape, such as Hi-8 and DVC, have appeared on the market. Because the thin metal film of ME tape is highly rigid, it is difficult to obtain a good head contact, i.e., satisfactory read and write characteristics, unless the magnetic head keeps a sharp tip. Containing no abrasive grains, ME tape shows little running-in behavior with the magnetic head and therefore has poor conformity or frictional compatibility with the head. On the other hand, since the magnetic layer of the MP tape has magnetic powder dispersed in a binder, the touch of the magnetic tape to the magnetic head is soft so that the shape of the head tip is not so influential on the head contact of the tape. Furthermore, the magnetic powder exerts wearing effect to have satisfactory conformity to the magnetic head. Accordingly, when MP tape runs on a magnetic head on which ME tape has run, there is no appreciable change in head contact. To the contrary, when ME tape runs after MP tape has run, poor head contact can result.
JP-A-62-92205 discloses a double-layered polishing tape used to polish a magnetic head comprising a nonmagnetic support, an intermediate layer containing nonmagnetic powder formed on the support, and an abrasive layer containing a nonmagnetic abrasive formed on the intermediate layer. The polishing tape is designed such that the intermediate layer has a rough surface profile and that the upper abrasive layer contains fine abrasive particles so as to prevent scratching a magnetic head while maintaining necessary abrasive force. However, the tape is for finish-polishing a magnetic head, and it abrades a head too much to be used as a cleaning tape for carrying out moderate abrasion, as is understood from its surface roughness of from 0.03 to 0.3 μm. A similar double-layered polishing tape is disclosed in JP-A-62-94270. With this tape, too, it is difficult to perform cleaning by moderate abrasion without scratching a magnetic head. The tape is therefore unfit for use as a cleaning medium.
As stated, the demand for minimizing a wear of an MR head is stricter than for a ferrite head or a metal (e.g., Sendust) head. An effective solution to this issue has been awaited.